1. Field of the Invention
This invention relates to a fixation ring for radial keratotomy, which affords teeth or is formed as a vacuum ring, for the temporary fixation or the immobilization of the human eye in situ.
2. Description of the Prior Art
The method of radial keratotomy is generally known in ophthalmology, and it serves for the modification of the refraction of the human cornea. In radial keratotomy, there are formed, with a cutting apparatus, such as a knife, cuts of a given depth in the cornea. Commonly, the cuts are between 0.05 and 0.65 millimeter deep. Such a method permits corrections of myopia up to about minus 8 diopters. By producing such cuts, a desired weakening of the cornea in its periphery is produced, so that it can be subjected to pressure from the inner pressure of the eye, and the cornea can thereby be flattened. With the flattening of the cornea, the refractive power of the eye is diminished, and the focal point is moved to the retina from the plane of the vitreous humor of the eye, in which it lies in the case of myopia. The desired effect of this method is among other things dependent upon the size of the uncut optical zone in the center of the cornea, as well as the depth and the length of the cuts.
Prior to the present invention, the cuts have been made free-hand, the surgeon moving a steel knife or a special cutting apparatus with a protruding diamond either from the periphery towards the center of the optical zone or the reverse. For the surgeon, it is particularly difficult to guide the knife always perpendicular to the tangent of the cornea's outer surface. However, if the knife contacts the cornea surface diagonally, there are developed other, uncalculable conditions, which can lead to an increased fluctuation in the results of the various operations.